>> reporter: we learned inappropriate message between general petraeus and paula broadwell were discovered by accident. the f.b.i. wasn't originally aware of the affair between the two but learned of their relationship while trying to track down the origin of some harassing e-mails. >> what i have been told is that there was somebody else that he knew and was close to. mrs. broadwell sent threatening e-mails to her. she was frightened and went to the f.b.i. >> reporter: senator feinstein heads the intelligence committee and said she had no heads up. and when she found out on friday it was a lightning bolt. the white house says president obama found out about the affair on thursday of this week. the chairman of the house homeland security committee peter king doesn't understand why the f.b.i. wouldn't notify him of something like this immediately. >> i have a hard time believing the whole story. first of all, how an e-mail issue becomes an f.b.i. matter. how it was investigated for so many months. how it wasn't until election night that the f.b.i. suddenly realized it involved david petraeu